Caffeine-Induced Contraction in Arteries from Stroke-Prone Spontaneously Hypertensive Rats

Abstract

Differences in caffeine-induced contraction in smooth muscle of resistance vessels from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar Kyoto rats (WKY) were investigated by using mesenteric artery preparations. The contraction induced by caffeine (10 mM) was greater in SHRSP preparations, both in the presence and absence of Ca (10 min after Ca removal). Caffeine-induced contraction was gradually decreased by the removal of extracellular Ca. No significant difference was observed in the time course of the decay of the contraction between SHRSP and WKY preparations, and the contraction disappeared when the time in Ca-free solution exceeded 80 min. The contraction induced by high-K-Tyrode’s solution was completely abolished within 10 min after Ca removal, both in SHRSP and WKY preparations. Caffeine-induced contraction could be blocked by procaine or ryanodine. The results suggest that caffeine induces contraction by releasing Ca from sarcoplasmic reticulum, and that the release of Ca is greater in SHRSP vascular smooth muscle. It is also suggested that sarcoplasmic reticulum is leaky for stored Ca when extracellular Ca is removed, and that the rate of leakage does not differ between smooth muscle cells of SHRSP and WKY mesenteric arteries.

Increased Ca2+ Buffering Function of Sarcoplasmic Reticulum in Small Mesenteric Arteries from Spontaneously Hypertensive Rats

“…A larger contraction induced by caffeine has also been reported in the small mesenteric arteries from stroke-prone SHR (SHRSP) (24) and in the aorta (17), femoral artery (9) and carotid artery (19) from SHR. In the tail artery the caffeine contraction was the same for the two strains (20).…”

Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles

“…Early studies found that caffeine-induced contraction of mesenteric resistance arteries (1033) and aortas (727) is increased in vessels from SHRSP versus WKY rats and that this is likely due to an increased Ca 2+ load in the SR (727). RyR function also appears to be enhanced in SMCs from SHR versus WKY rats (276).…”

Coffee, caffeine and blood pressure: a critical review

“…Caffeine produced transient contractions of arterial smooth muscle at millimolar concentrations in vitro (Kalsner, 1971;Karaki et al, 1987;Sato et al, 1988;Moriyama et al, 1989), which were more marked in preparations from spontaneously hypertensive rats than from normotensive rats (Moriyama et al, 1989). Caffeine-induced vascular contractions were reduced or blocked by removal of extracellular calcium or by the inhibition of calcium release from the sarcoplasmic reticulum (Sato et al, 1988;Moriyama et al, 1989).…”

“…Caffeine-induced vascular contractions were reduced or blocked by removal of extracellular calcium or by the inhibition of calcium release from the sarcoplasmic reticulum (Sato et al, 1988;Moriyama et al, 1989). It has been suggested that the mobilization of intracellular calcium by the so-called calciuminduced calcium release mechanism is crucial in caffeineinduced vasoconstriction (Karaki et al, 1987).…”